Various scientific and scholarly articles are referred to throughout the specification. These articles are incorporated by reference herein to describe the state of the art to which this invention pertains.
Polyaromatic hydrocarbons (PAHs) are widespread pollutants, particularly in conjunction with the marine environment. High PAH levels are known to be toxic, mutagenic and carcinogenic, and therefore pose a considerable threat to the public health. Many microorganisms degrade PAHs, and there is a strong interest in applying bioremediation approaches to remove PAHs from the environment.
Bacteria that degrade 2-3 ring low molecular weight polyaromatic hydrocarbons, such as naphthalene, phenanthrene, bi-phenyl and fluorene, are taxonimically diverse. Gram negative genera such as Pseudomonas, Burkholderia, Alcaligens, Sphingomonas, Vibrio and Comamonas are common. While less common, the gram-positive species such as Mycobacterium, Nocardia, Rhodococcus and Gordona are also known to degrade low molecular weight PAHs.
Microorganisms that can degrade the 4-ring and higher high molecular weight PAHs such as pyrene, fluoranthene and benz[a]anthracene are much rarer. The degradation of high molecular weight PAHs is much slower and less extensive than the degradation of low molecular weight PAHs in the environment.
The isolation of new genera of PAH-degrading bacteria is sought, particularly species with novel combinations of growth and degradative characteristics. In particular, species are sought with a broad range of PAH specificities. Species that can degrade the higher molecular weight PAHs are particularly valuable. Finally, PAH-degrading species that are capable to surviving adverse nutritional and environmental conditions by forming endospores are of particular interest.